Re: [PATCH v2] x86/power/64: Support unaligned addresses for temporary mapping

[Rafael J. Wysocki]

On Wed, Aug 3, 2016 at 8:23 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> From: Thomas Garnier <thgarnie@xxxxxxxxxx>
>
> Correctly setup the temporary mapping for hibernation. Previous
> implementation assumed the offset between KVA and PA was aligned on the PGD level.
> With KASLR memory randomization enabled, the offset is randomized on the PUD
> level. This change supports unaligned up to PMD.
>
> Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxx>
> [yinghai: change loop to virtual address]
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

> ---
>  arch/x86/mm/ident_map.c |   54 ++++++++++++++++++++++++++++--------------------
>  1 file changed, 32 insertions(+), 22 deletions(-)
>
> Index: linux-2.6/arch/x86/mm/ident_map.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/mm/ident_map.c
> +++ linux-2.6/arch/x86/mm/ident_map.c
> @@ -3,40 +3,47 @@
>   * included by both the compressed kernel and the regular kernel.
>   */
>
> -static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
> +static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
>                            unsigned long addr, unsigned long end)
>  {
> -       addr &= PMD_MASK;
> -       for (; addr < end; addr += PMD_SIZE) {
> -               pmd_t *pmd = pmd_page + pmd_index(addr);
> +       unsigned long off = info->kernel_mapping ? __PAGE_OFFSET : 0;
> +       unsigned long vaddr = addr + off;
> +       unsigned long vend = end + off;
> +
> +       vaddr &= PMD_MASK;
> +       for (; vaddr < vend; vaddr += PMD_SIZE) {
> +               pmd_t *pmd = pmd_page + pmd_index(vaddr);
>
>                 if (!pmd_present(*pmd))
> -                       set_pmd(pmd, __pmd(addr | pmd_flag));
> +                       set_pmd(pmd, __pmd((vaddr - off) | info->pmd_flag));
>         }
>  }
>
>  static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
>                           unsigned long addr, unsigned long end)
>  {
> -       unsigned long next;
> +       unsigned long off = info->kernel_mapping ? __PAGE_OFFSET : 0;
> +       unsigned long vaddr = addr + off;
> +       unsigned long vend = end + off;
> +       unsigned long vnext;
>
> -       for (; addr < end; addr = next) {
> -               pud_t *pud = pud_page + pud_index(addr);
> +       for (; vaddr < vend; vaddr = vnext) {
> +               pud_t *pud = pud_page + pud_index(vaddr);
>                 pmd_t *pmd;
>
> -               next = (addr & PUD_MASK) + PUD_SIZE;
> -               if (next > end)
> -                       next = end;
> +               vnext = (vaddr & PUD_MASK) + PUD_SIZE;
> +               if (vnext > vend)
> +                       vnext = vend;
>
>                 if (pud_present(*pud)) {
>                         pmd = pmd_offset(pud, 0);
> -                       ident_pmd_init(info->pmd_flag, pmd, addr, next);
> +                       ident_pmd_init(info, pmd, vaddr - off, vnext - off);
>                         continue;
>                 }
>                 pmd = (pmd_t *)info->alloc_pgt_page(info->context);
>                 if (!pmd)
>                         return -ENOMEM;
> -               ident_pmd_init(info->pmd_flag, pmd, addr, next);
> +               ident_pmd_init(info, pmd, vaddr - off, vnext - off);
>                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
>         }
>
> @@ -46,21 +53,24 @@ static int ident_pud_init(struct x86_map
>  int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
>                               unsigned long addr, unsigned long end)
>  {
> -       unsigned long next;
>         int result;
> -       int off = info->kernel_mapping ? pgd_index(__PAGE_OFFSET) : 0;
> +       unsigned long off = info->kernel_mapping ? __PAGE_OFFSET : 0;
> +       unsigned long vaddr = addr + off;
> +       unsigned long vend = end + off;
> +       unsigned long vnext;
>
> -       for (; addr < end; addr = next) {
> -               pgd_t *pgd = pgd_page + pgd_index(addr) + off;
> +       for (; vaddr < vend; vaddr = vnext) {
> +               pgd_t *pgd = pgd_page + pgd_index(vaddr);
>                 pud_t *pud;
>
> -               next = (addr & PGDIR_MASK) + PGDIR_SIZE;
> -               if (next > end)
> -                       next = end;
> +               vnext = (vaddr & PGDIR_MASK) + PGDIR_SIZE;
> +               if (vnext > vend)
> +                       vnext = vend;
>
>                 if (pgd_present(*pgd)) {
>                         pud = pud_offset(pgd, 0);
> -                       result = ident_pud_init(info, pud, addr, next);
> +                       result = ident_pud_init(info, pud, vaddr - off,
> +                                               vnext - off);
>                         if (result)
>                                 return result;
>                         continue;
> @@ -69,7 +79,7 @@ int kernel_ident_mapping_init(struct x86
>                 pud = (pud_t *)info->alloc_pgt_page(info->context);
>                 if (!pud)
>                         return -ENOMEM;
> -               result = ident_pud_init(info, pud, addr, next);
> +               result = ident_pud_init(info, pud, vaddr - off, vnext - off);
>                 if (result)
>                         return result;
>                 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
> --
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